Re: H. bullocki 'colour forms' mating

August 6, 2002
From: Erwin Koehler

Dear Bill,
It looks like nobody is interested in interspecies mating problems ...
Here some words on it: In my youth I collected butterflies, focussing on Sphingidae (Common names: sphinx moths, hawk moths). There were several records of interspecies mating in the field and of course in the lab: Smerinthus ocellata and Laothoe populi.
The next generation was reported to be unfertile.

Koehler, E., 2002 (Aug 6) Re: H. bullocki 'colour forms' mating. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Thanks Erwin,
I am glad someone noticed my plea for a discussion. There are examples of interspecies mating, usually resulting in infertile offspring, but in terms of all life on earth, they are a rarity. The question I am trying to get discussed is not whether interspecies mating can occur but whether it is a sensible suggestion in the case of the Hypselodoris bullocki group of species. It seems to me that the argument is starting to look a bit circular. My first thought when seeing two animals mating, is that they are the same species, and if they are distinctly different in shape and colour from one another, it would suggest that there is either sexual dimorphism (in species with separate males and females) or polymorphism within the species. In your butterfly days you must have seen examples of polymorphic butterflies and moths, in which there can be 2, 3, or more, distinct colour patterns within the one species.

The alternative in the case of H. bullocki, is to argue that there are a number of species, very similar in shape and anatomy but different in colour pattern - and by the way, they interbreed with each other! It doesn't sound very convincing to me.
Bill Rudman

Rudman, W.B., 2002 (Aug 6). Comment on Re: H. bullocki 'colour forms' mating by Erwin Koehler. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

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